CHICAGO (AP) — Thousands of Oprah Winfrey fans are expected to pack Chicago's United Center on Tuesday for a star-studded double-taping of her talk show as it approaches its finale.

The guest lineup for "Surprise Oprah! A Farewell Spectacular" is a secret, but Winfrey's producers have promised the biggest names in Hollywood.

The celebrity response "has been a resounding 'yes,'" executive producer Sheri Salata said.

"Celebrities from film, television and music feel a deep appreciation for the support they have received from Oprah and the show over the years," Salata said. "Oprah will be very touched by that gratitude."

Tuesday's taping will air May 23 and 24, before Winfrey's final show on May 25.

The content of the final episode of "The Oprah Winfrey Show" is still under wraps. Winfrey announced in November 2009 that she would end her popular talk show after 25 years.

"Oprah is in great spirits, energized and taking in every last bit of these final days," said Salata, who figures prominently on "Season 25: Oprah Behind the Scenes." The show follows the final season Winfrey's talk show and airs on her new cable network.

"The producers are a little teary-eyed — it's hard to say goodbye," Salata said.

Harpo Productions received more than 154,000 ticket requests for seats to Tuesday's event. Tickets were free and distributed to fans through a lottery.

The United Center is home to the Chicago Bulls and Chicago Blackhawks with a seating capacity of more than 20,000. It is just blocks from Winfrey's long-time studios.

It isn't the first time Winfrey has staged a blockbuster event in Chicago.

The crowd was estimated at 21,000 when Winfrey closed down Chicago's Michigan Avenue in September 2009 to film her 24th season premiere.